Heretofore, silver halide photographic materials have been substantially incapable of accepting input of various data for picture taking (e.g., date of picture taking, weather, enlargement ratio and number of prints) and only capable of accepting an optical input of the date of picture taking.
Further, the prior art silver halide photographic materials have been totally incapable of accepting input of their own data, thereby drastically hindering high speed operation and cost reduction.
Inputting various data into light-sensitive materials is an important means for improving and further simplifying the convenience of cameras. An example of such a data inputting means is a magnetic recording method, which advantageously enables arbitrary input and output of data at a low cost.
For example, U.S. Pat. Nos. 3,782,947, 4,279,945, and 4,302,523 propose that the back surface of a light-sensitive material comprising a transparent support be coated with a magnetic recording layer which exhibits a necessary transparency for light-sensitive material upon picture taking and does not affect the granularity of a light-sensitive material by properly selecting the amount and size of magnetizable grains contained in the magnetic recording layer. The system of inputting a signal into a magnetic recording layer is disclosed in World Patent Disclosure Nos. 90-4205 and 90-04212.
The provision of such a magnetic recording layer and a system of inputting and outputting signal into a magnetic recording layer enables the incorporation of various data into a light-sensitive material, which has been heretofore difficult to perform. For example, various conditions such as those for picture taking (e.g., date of picture taking, weather, illumination condition and reduction/enlargement ratio) and those upon development and printing (e.g., number of reprints, portions to be zoomed and messages) can be inputted to or outputted from the magnetic layer on the light-sensitive material. Further, it can be expected in the future that the magnetic recording layer can be used as a signal input/output means in a system wherein a signal is outputted directly from a light-sensitive material to a television/video equipment for picture display.
However, the use of magnetic powder as described in the above-cited patents causes many disadvantages. For example, the magnetic powders exhibit poor wetting with a binder medium or cause magnetic agglomeration among grains. This makes it difficult to disperes uniformly the powder in a binder resin. Even when a mechanical dispersion is effected, if the binder resin is used in an amount larger than that of the magnetic powder, agglomeration can occur or the magnetic properties of the magnetic recording medium can be reduced. In particular, if a binder mainly comprising a polyurethane resin is used, the above-mentioned tendency becomes remarkable. Further, even if it is attempted to form a photographically transparent magnetic recording layer which is an object of the present invention, the resulting layer is not transparent due to the presence of agglomerate of magnetic materials.